Haptic feedback using rotary harmonic moving mass

ABSTRACT

A haptic device comprises an actuator and a mass. The actuator has a shaft. The actuator is elastically coupled to the mass and/or a base.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to co-pending U.S. patent applicationNo. 60/375,930, entitled “Haptic Feedback Using Rotary Harmonic MovingMass,” filed on Apr. 25, 2002, the entirety of which is incorporatedherein by reference.

BACKGROUND

The present invention relates generally to haptic feedback devices, andmore particularly to vibrations and similar force sensations producedfrom a haptic feedback device.

An interface device can be used by a user to provide information to acomputer device or an electronic device. For example, with a computerdevice, a user can interact with an environment displayed by thecomputer to perform functions and tasks on the computer, such as playinga game, experiencing a simulation or virtual reality environment, usinga computer aided design system, operating a graphical user interface(GUI), or other affecting processes or images depicted on an outputdevice of the computer. In addition, a user can interact with theelectronic device, for example, using a remote control, a wirelessphone, or stereo controls. Common human interface devices for suchcomputer devices or electronic devices include, for example, a joystick,button, mouse, trackball, knob, steering wheel, stylus, tablet, andpressure-sensitive ball.

In some interface devices, force feedback or tactile feedback is alsoprovided to the user, also known more generally herein as “hapticfeedback.” These types of interface devices can provide physicalsensations that are felt by the user using the controller ormanipulating a physical object of the interface device. Each of theseinterface devices includes one or more actuators, which are connected toa controlling processor and/or computer system. Consequently, acontrolling processor and/or computer system can control haptic forcesproduced by the haptic feedback device in coordination with actions ofthe user and/or events associated with a graphical or displayedenvironment by sending control signals or commands to the actuator(s) ofthe haptic feedback device.

Many low cost haptic feedback devices produce haptic forces, forexample, by vibrating the manipulandum and/or the housing of the hapticfeedback devices while being held by users. One or more haptic devicescan be activated to provide the vibration forces. This can beaccomplished, for example, by rotating an eccentric mass coupled to theshaft of each haptic device. As a result, the housing also vibrates. Twodifferent haptic devices can be used: one haptic device having a largermass provides low frequency rumbles and another haptic device having asmaller mass provides higher frequency vibrations.

These known haptic feedback devices, however, suffer severalshortcomings. First, single-actuator systems having a relatively largerotating mass are effective at providing rough, high magnitudesensations, but are ineffective at providing subtle, high frequencyvibrations, thereby severely limiting the variety of haptic feedbackeffects that can be experienced by a user of these haptic feedbackdevices. One attempted solution to this problem has been the use of asecond haptic device with a smaller rotating mass. Even this attemptedsolution, however, is costly and uses a relatively large amount ofspace.

Finally, starting and stopping the rotation of the eccentric massconnected to the actuator involves time delays. These time delays, whichcan be as long as about 0.1 second, present a challenge in synchronizingthe produced haptic forces with the events, actions or interactions in acomputer simulation, game, device, etc. In addition, the delays instarting or stopping the rotation of the eccentric mass are notnecessarily constant thereby presenting additional synchronizationchallenges.

Thus, a need exists for improved haptic feedback devices.

SUMMARY OF THE INVENTION

A haptic device comprises an actuator and a mass. The actuator has ashaft. The actuator is elastically coupled to the mass and/or a base.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 depict a perspective view and a top view, respectively, ofa haptic device, according to an embodiment of the invention.

FIGS. 3 and 4 depict a perspective view and a top view, respectively, ofa haptic device having two compliant portions, according to anembodiment of the invention.

FIGS. 5 and 6 show a position bode plot and an acceleration bode plot,respectively, as a function of the damping ratio for a haptic deviceoperating in a harmonic mode, according to embodiments of the invention.

FIGS. 7 and 8 show a position bode plot and an acceleration bode plot,respectively, as a function of the spring constant for a haptic deviceoperating in a harmonic mode, according to embodiments of the invention.

FIGS. 9 and 10 show a position bode plot and an acceleration bode plot,respectively, as a function of the mass for a haptic device operating ina harmonic mode, according to embodiments of the invention.

FIGS. 11 and 12 show a position bode plot and an acceleration bode plot,respectively, as a function of the eccentric radius for a haptic deviceoperating in a harmonic mode, according to embodiments of the invention.

FIG. 13 shows a perspective view of a haptic device having a leafspring, according to an embodiment of the invention.

FIG. 14 shows a perspective view of a haptic device having a leafspring, according to another embodiment of the invention.

FIG. 15 shows a perspective view of a haptic device having apolypropylene elastic member, according to an embodiment of theinvention.

FIG. 16 shows a perspective view of a haptic device having apolypropylene elastic member, according to another embodiment of theinvention.

FIG. 17 shows a perspective view of a mass and elastic member for ahaptic device, according to an embodiment of the invention.

FIG. 18 shows a perspective view of a haptic device, according toanother embodiment of the invention.

FIG. 19 shows a perspective view of a haptic device having an elasticmember coupling an actuator to a base, according to another embodimentof the invention.

FIGS. 20 and 21 show perspective views of a haptic device having anelastic member coupling an actuator to a base, according to anotherembodiment of the invention.

FIGS. 22 and 23 show perspective views of a haptic device having anelastic member coupling an actuator to a base, according to yet anotherembodiment of the invention.

FIG. 24 shows a perspective view of a haptic device having two actuatorsthat share a common rotation axis and a common mass, according to anembodiment of the invention.

FIGS. 25 and 26 show perspective views of a haptic device having twoactuators that share a common rotation axis and a common mass, accordingto another embodiment of the invention.

FIG. 27 shows a top view of a haptic device having limiting stops,according to another embodiment of the invention.

FIG. 28 shows a top view of a haptic device having limiting stops,according to another embodiment.

FIGS. 29 and 30 show a perspective view of a haptic device having stopsintegrally formed with an elastic member according to an embodiment ofinvention.

DETAILED DESCRIPTION

Generally speaking, embodiments described herein relate to hapticdevices each of which produces a haptic feedback force through aharmonic spring/mass system. Such a system can include one or moremoving masses combined with one or more spring components. The use ofthe term “spring/mass system” is in reference to any type of systemhaving an elastically or flexibly coupled mass. Such an elastic orflexible coupling can be via, for example, a spring or flexible member.Thus, any references herein to an elastic member or elastic coupling canalso apply to a flexible member or flexible coupling.

These haptic devices can be coupled (e.g., by mechanical mounting) to orwithin a housing to provide haptic feedback force to the user of thehousing. The housing can be, for example, for a game controller, acommunication device, a remote control, a stereo controller, or a humaninterface device for computer devices or electronic devices such as ajoystick, button, mouse, trackball, knob, steering wheel, stylus, tabletor pressure-sensitive ball.

In many embodiments, a haptic device comprises an actuator and a mass.The actuator has a shaft. The actuator is elastically coupled to themass and/or a base. In one embodiment, the actuator is a rotaryactuator, the mass is an eccentric mass and the shaft of the rotaryactuator is elastically coupled to the eccentric mass by an elasticmember. In this embodiment, the rotary actuator, the eccentric mass andelastic member of the haptic device collectively have a firstoperational mode associated with a range of frequencies and a secondoperational mode associated with a range of frequencies different fromthe range of frequencies associated with the first operational mode. Forexample, the first operational mode can be based on a unidirectionalrotation of the mass about the shaft of the rotary actuator; the secondoperational mode can be based on a harmonic motion of the mass.

Embodiments of the haptic devices described herein address many of theshortcomings of known haptic devices described above in the backgroundsection. For example, the haptic device embodiments described hereinallow independent control of the vibration magnitude and frequency overan extended range of frequencies. In addition, a single actuator canproduce both low frequency vibrations, for example using the operationalmode based on unidirectional rotation of the mass, and high frequencyvibrations, for example using the operational mode based on the harmonicmotion of the mass. The actuator can operate in either operational modesingularly or in both operational modes at overlapping times to producea superposition of low frequency vibrations and high frequencyvibrations. Also, the time delays associated with starting and stoppingvibrations can be smaller than that of known haptic devices.

The term “operational mode” is used herein to mean a manner of operationof an actuator. Such an operational mode can be described, for example,in reference to the signal applied to the actuator. For example, oneoperational mode of the actuator can relate to direct current (DC)signals applied to the actuator. In this operational mode (also referredto herein as a “unidirectional mode”), the operation of the actuatorresults in centripetal acceleration of the mass coupled to the actuatorwithin a range of frequencies associated with the unidirectional mode.Another operational mode of the actuator, for example, can relate toalternating current (AC) signals (e.g., signals with reversing polarity)applied to the actuator. In this operational mode (also referred toherein as a “harmonic mode”), the actuator drives the mass alternativelyin opposite directions within a range of frequencies associated with theharmonic mode. In an alternative embodiment, the harmonic mode can beaccomplished by providing the actuator with a unidirectional voltage atthe harmonic frequency. Following this example, it is possible that asingle signal provided to the actuator can result in both theunidirectional mode and the harmonic mode, for example, wherefrequencies associated with the harmonic mode overlap with thefrequencies associated with the unidirectional mode.

Note that the range of frequencies associated with the unidirectionalmode is typically different from the range of frequencies associatedwith the harmonic mode. These ranges of frequencies can be, for example,mutually exclusive or, alternatively, one range can be a subset of theother. For example, the range of frequencies associated with theunidirectional mode can be 10-40 Hz and the range of frequenciesassociated with the harmonic mode can be 5-250 Hz. In this example, therange of frequencies associated with the unidirectional mode is a subsetof the range of frequencies associated with the harmonic mode. Saidanother way, the vibration frequencies potentially produced while theactuator is operating in the unidirectional mode are a subset of thevibration frequencies potentially produced while the actuator isoperating in the harmonic mode. In other embodiments, the range offrequencies associated with the unidirectional mode is mutuallyexclusive from the range of frequencies associated with the harmonicmode. In yet other embodiments, the range of frequencies associated withthe unidirectional mode partially overlaps with the range of frequenciesassociated with the harmonic mode.

Another operational mode of the actuator can relate to a superpositionof the unidirectional mode and the harmonic mode. In this operationalmode (also referred to herein as the “superposition mode”), the actuatorcan be simultaneously driven by DC signals and AC signals, therebyresulting in centripetal acceleration of the mass coupled to theactuator within the range of frequencies associated with theunidirectional mode while also driving the mass in opposite directionswithin the range of frequencies associated with the harmonic mode.Following the example of above, an actuator operating in thesuperposition mode can result simultaneously in a vibration frequencybetween 10 and 40 Hz and one or more vibration frequencies between 5 and250 Hz. The ranges described herein are for illustrative purposes; anyrange practicable can be used by embodiments described herein.

In some embodiments, more than the unidirectional mode, harmonic modeand the superposition mode are possible. Such embodiments can have, forexample, more than one structure associated with a harmonic mode. Forexample, a first mass can be elastically coupled to a rotary actuatorand a second mass can be elastically coupled to the first mass. In suchan embodiment, one harmonic mode can be associated with the elasticcoupling between the actuator and the first mass, and a differentharmonic mode can be associated with the elastic coupling between thefirst mass and the second mass. In another example, two masses can beelastically coupled to the shaft of a rotary actuator with two differentspring constants. Consequently, superposition of two or more modes, aunidirectional mode, a first harmonic mode and a second harmonic mode,is possible. Embodiments having any number of harmonic modes are alsopossible.

Although many of the embodiments described herein relate to a rotaryactuator coupled to a mass rotating about the shaft of the actuator,non-rotary embodiments are possible. For example, one embodimentcomprises a spring that expands and contracts along an axis where thespring is coupled at one end to a mass and coupled at the other end to ashaft of an actuator; the shaft translates along the axis. In otherembodiments, the actuator is a pancake motor or a motor with a hollowcore. In general, the actuator can be any type of mechanism thatgenerates torque.

Moreover, although many embodiments described herein relate to rotarysystems where the rotation is within a plane transverse to the actuatorshaft, alternative embodiments are possible where the rotation is notwithin a plane. For example, an elastic member coupling the mass to theactuator can have elasticity in a direction other than or in addition tothe rotation direction. In such embodiments, the harmonic mode caninvolve non-planar movement of the mass.

The term “actuator” as used herein refers to a motion actuator thatcauses motion. For example, such an actuator can be, for example, amotor, a piezoelectric structure and a voice coil. This is distinguishedfrom a haptic-force actuator that causes haptic force. For clarity, sucha haptic-force actuator is referred to herein as a haptic device. Thus,an actuator (a motion actuator) can be included within a actuator device(a haptic-force actuator).

The term “elastic member” is used herein to mean any type of structuremade of a material that tends to return to an initial form or stateafter deformation. Such an elastic member can be, for example, a plasticor rubber structure, or a metal structure such as a leaf spring orhelical spring. The elastic member is elastic in the sense that it hasan appropriate elasticity such that a harmonic mode is possible. Forexample, for embodiments where the actuator is a rotary actuator with anelastically coupled eccentric mass, the elasticity of the elasticcoupling is sufficient to allow the mass to move in a harmonic modeeither in superposition with the unidirectional mode or withoutsuperposition of the unidirectional mode.

The term “haptic” is used herein to relate to the sense of touch, alsoreferred to as tactile. Thus, a haptic device is a device that transfersforces to a user, for example, under the direction of a computer orelectronic device thereby allowing the user to interact or interfacewith the computer or electronic device in a physically tactile way.Although different names can be used to convey the many subtledifferences in how these haptic devices operate, they all fall withinthe term “haptic”. Such different names include tactile feedback, fullforce feedback, vibro-tactile, rumble feedback, touch-enabled,touch-activated and refer to different ways in which haptic devices canoperate. For example, rumble feedback typically refers to low-fidelityshakes or rumbles popular with game controllers and used in conjunctionwith high-action events in a game.

FIGS. 1 and 2 depict a perspective view and a top view, respectively, ofa haptic device, according to an embodiment of the invention. As shownin FIGS. 1 and 2, haptic device 100 includes an actuator 110, an elasticmember 120 and a mass 130. Actuator 110, which is a rotary actuator,includes a shaft 115. Elastic member 120 includes a proximate portion121, a compliant portion 122 and a distal portion 125. The proximateportion 121 of elastic member 120 is coupled to the shaft 115 ofactuator 110. The distal portion 125, which has a width greater than thecompliant portion 122, is coupled to mass 130.

Actuator 110 can be any type of rotary actuator such as, for example, adirect current (DC) motor, voice coil actuator or a moving magnetactuator. In addition, actuator 110 can be disposed in and mechanicallygrounded to a device housing (not shown), such as in a game controllerhousing. Examples of haptic devices disposed in and mechanicallygrounded to game controller housings are disclosed in application Ser.Nos. 09/967,494 and 09/967,496, the disclosure of which are bothincorporated herein by reference.

Although elastic member 120 is shown as being integrally formed in aunitary construction among the proximate portion 121, compliant portion122 and distal portion 125, other configurations are possible. Where thecompliant portion is made of a flexible material, the proximate portionand the distal portion need not be made of flexible materials and neednot be integrally formed with the compliant portion. For example, thecompliant portion of an elastic member can be coupled to the mass and/orthe shaft of the actuator by separate couplings or fasteners. Similarly,the elastic member can be of various types including, for example, leafsprings or helical springs.

Actuator 110, elastic member 120 and mass 130 of haptic device 100collectively have a first operational mode associated with a range offrequencies and a second operational mode associated with a range offrequencies different from the range of frequencies associated with thefirst mode. For example, the first mode can be based on a unidirectionalrotation of mass 100 about shaft 115 of the actuator 110 (also referredto herein as the “unidirectional mode”); the second mode can be based ona harmonic motion of the mass (also referred to herein as the “harmonicmode”).

More specifically, elastic member 120 coupled between shaft 115 ofactuator 110 and mass 130 results in a harmonic system. In a harmonicsystem, the electrical driving signal and resulting motor torque actagainst a conservative mechanical system. Such a harmonic systemexhibits second order behavior with the magnification of vibrations atcertain frequencies (e.g., at a resonance frequency of the mechanicalsystem). Here, haptic device 100 is configured as a harmonic systemwhere elastic member 120 stores energy and releases it while in theharmonic mode. Said another way, the compliant portion 122 of elasticmember 120 stores energy during the movement of mass 130 in response toone polarity of the AC drive signal and releases the energy during themovement of mass 130 in response to the other polarity of the AC drivesignal. This results in harmonic motion and corresponding amplificationthrough broad resonance. This results in high magnitude vibrations andother effects in a power-efficient manner. In addition, complex AC drivesignals having many different frequency components can be superimposedon each other while haptic device 100 operates in the harmonic mode.

The inventors have recognized that it is advantageous for the dampingfactor of the mechanical system to be low. This may result in a moreefficient harmonic vibration. Consequently, the compliant portion 122 ofthe elastic member 120 can be made of polypropylene, which exhibits alow damping. Alternatively, the elastic member can be made of steel,wire, plastic or other similar types of materials that can connect themass 130 in series with the shaft 115 of the actuator 110.

When operating in the unidirectional mode, actuator 110 can be driven,for example, with a DC current, thereby causing mass 130 to rotate aboutthe shaft 115 of actuator 110 with centripetal acceleration. Thiscentripetal acceleration provides strong inertial forces against thedevice housing. Firmware techniques can be used to control the magnitudeof the vibrations while operating in the unidirectional mode. Forexample, a certain pulse-repetition rate having a 50% duty cycle resultsin mass 130 rotating unidirectionally at a certain rate with half of thevibration magnitude that would otherwise result from applying a constantvoltage (i.e., 100% duty cycle). Further examples of such firmware aredisclosed in application Ser. No. 09/669,029, the disclosure of which isincorporated herein by reference.

When actuator 110 is operated in the harmonic mode, mass 130 oscillatesat or approximately at the frequency of the drive signal (e.g., an ACsignal driving actuator 110). Such a drive signal can be produced, forexample, by an H-bridge circuit or other amplifier. This advantageouslyinvolves smaller time delays in starting and stopping movement of themass than is the case with motion of the mass in the unidirectionalmode.

Although FIGS. 1 and 2 show an elastic member having a single compliantportion, alternative embodiments of an elastic member having multiplecompliant portions are possible. For example, FIGS. 3 and 4 depict aperspective view and a top view, respectively, of a haptic device havingtwo compliant portions, according to an embodiment of the invention. Asshown in FIGS. 3 and 4, haptic device 200 includes an actuator 210, anelastic member 220 and a mass 230. Actuator 210, which is a rotaryactuator, includes a shaft 215. Elastic member 220 includes a proximateportion 221, compliant portions 222 and 223, and distal portions 225 and226. The proximate portion 221 of elastic member 220 is coupled to theshaft 215 of actuator 210. The distal portions 225 and 226, each ofwhich have a width greater than the compliant portions 222 and 223, arecoupled to mass 230. Although elastic member 220 shown in FIGS. 3 and 4has two compliant portions 222 and 223, other embodiments are possiblewhere the elastic member has greater than two compliant portions.

Note that the compliant portion(s) can be compliant in one degree offreedom or axis of travel of mass, but need not be compliant in theremaining degrees of freedom. For example, compliant portion 122 (shownin FIGS. 1 and 2) can be inflexible in the direction parallel to theaxis of rotation along shaft 115 of actuator 110. Similarly, compliantportions 222 and 223 can each be inflexible in the direction parallel tothe axis of rotation along shaft 215 of actuator 210. As best shown inFIG. 3, compliant portions 222 and 223 can be relatively thick along thedirection parallel to shaft 215 of actuator 210.

In another embodiment, a haptic device includes a variable-stiffnessmechanical actuator. If the spring constant (K) value of a compliantportion of an elastic member can be varied as a function of drivefrequency, then the haptic device can operate near a peak magnificationand efficiency. A variable-stiffness mechanical actuator can be, forexample, a piezoelectric structure (e.g., a piezoelectric buzzer). Sucha piezoelectric structure can include, for example, a ceramic on a masswhere an applied voltage causes movement of the ceramic. Through theproper selection of the applied voltage, the ceramic can behave in amanner similar to a spring. The piezoelectric structure can change itsspring constant as a function of bias voltage. Consequently, afrequency-to-voltage converter driving the piezo structure element canmaintain a resonance frequency of the haptic device by adjusting thespring constant.

The particular behavior of a given embodiment of the haptic devicehaving a unidirectional mode and a harmonic mode (e.g., haptic device100 shown in FIGS. 1 and 2, and haptic device 200 shown in FIGS. 3 and4) can be modeled. Such a model can be based on various factors such as,for example, the mass shape and weight distribution, and the stiffnessof the compliant portion of the elastic member. The following provides adynamics model of an embodiment of the haptic device having aunidirectional mode and a harmonic mode.

The following equation is based on a second order Laplace transferfunction and can be used to model the harmonic mode of a haptic device:X/Tm=l/(r(ms^2+bs+k))where X is displacement, Tm is the torque of the motor, m is the weightof the mass, r is the eccentricity radius, k is the spring constant, bis the damping constant, and s is the Laplace variable. To be morespecific, the eccentricity radius, r, is the distance from center ofactuator shaft to center of mass of the mass.

The following equation can be used to model the unidirectional mode of ahaptic device:F=rω ² mwhere F is the force, ω is the angular velocity (2πf), f is thefrequency of the actuator.

The above defined dynamics model can be used to design a haptic devicehaving a harmonic mode. For example, the specific values of the dampingratio, the spring constant, the weight of the mass and the eccentricityradius can be selected to obtain a particular behavior of the hapticdevice. FIGS. 5 through 12 depict position and acceleration bode plotsfor a haptic device operating in the harmonic mode as a function of aparticular variable. The position bode plots show the amplitudedisplacement of the mass from an origin position for different drivesignal frequencies. The acceleration bode plots show the accelerationforce of the mass for different drive signal frequencies. With respectto FIGS. 5 and 6, the damping ratio, d, is related to the dampingconstant, b, by the equation: b/(2*sqrt(k)). Note that the y-axis unitshave been scaled for a motor capable of outputting 0.003 Nm of torque.The nominal comparison case is m=20 grams, damping ratio=0.15, k=1000N/m, r=10 mm, mp=250 grams. This nominal case results in a displacementof +/−1 mm with an acceleration of a mass in a linear actuator assemblyof +/−5 g, which equates to approximately 0.4 g to a 250-gram gamecontroller.

FIGS. 5 and 6 show a position bode plot and an acceleration bode plot,respectively, as a function of the damping ratio for a haptic deviceoperating in a harmonic mode, according to embodiments of the invention.As FIGS. 5 and 6 show, reducing the damping ratio results in a greaterposition displacement and acceleration of the mass. Thus, for someembodiments, it may be desirable to reduce the damping ratio below 0.15.

FIGS. 7 and 8 show a position bode plot and an acceleration bode plot,respectively, as a function of the spring constant for a haptic deviceoperating in a harmonic mode, according to embodiments of the invention.As FIGS. 7 and 8 show, the resonance frequency of the resonance mode ofthe haptic device is a function of the spring constant. Morespecifically, the peak-to-peak distance along the x-axis of the positiondisplacement of the mass shown in FIG. 7 changes as a function offrequency, while the peak-to-peak distance along the x-axis of theacceleration of the mass shown in FIG. 8 does not change significantlyas a function of frequency. Consequently, a haptic device having aharmonic mode can be designed for a specific resonance frequency byselecting a particular value for the spring constant.

FIGS. 9 and 10 show a position bode plot and an acceleration bode plot,respectively, as a function of the mass for a haptic device operating ina harmonic mode, according to embodiments of the invention. As FIGS. 9and 10 show, the resonance frequency and, in particular, the peakacceleration of the mass is a function of the weight of the mass. Asbest shown in FIG. 10, the amplitude of the acceleration of the massincreases with a decrease in the weight of the mass.

FIGS. 11 and 12 show a position bode plot and an acceleration bode plot,respectively, as a function of the eccentric radius for a haptic deviceoperating in a harmonic mode, according to embodiments of the invention.As FIGS. 11 and 12 show, the acceleration of the mass is a function ofthe eccentricity radius. Consequently, a lower eccentricity radiusresults in an increased displacement and acceleration of the mass whilethe harmonic device is operating in the harmonic mode. In other words, ashorter distance between the actuator shaft and the center of mass ofthe mass results in the actuator exerting greater force on the mass.Such a shorter eccentricity radius, however, can also result in a loweracceleration of the mass while the haptic device is in theunidirectional mode. Thus, the tradeoffs of the two factors can beconsidered in the design of a haptic device.

FIG. 13 shows a perspective view of a haptic device having a leafspring, according to an embodiment of the invention. As shown in FIG.13, haptic device 300 includes actuator 310, elastic member 320 and mass330. The actuator 310 includes a shaft (not shown) that rotates aboutaxis 326. The elastic member 320 includes compliant portion 322 andproximate portion 321. The compliant portion 322 is a leaf spring madeof, for example, metal having a thickness that allows flexibility.

FIG. 14 shows a perspective view of a haptic device having a leafspring, according to another embodiment of the invention. As shown inFIG. 14, haptic device 400 includes actuator 410, elastic member 420 andmass 430. The actuator 410 includes a shaft (not shown) that rotatesabout axis 425. The elastic member 420 includes compliant portion 422that is a leaf spring. Although similar to haptic device 300 shown inFIG. 13, haptic device 400 has a mass 430 larger in the dimensionparallel to axis 425 and compliant portion 422 that is shorter in theradial direction orthogonal to axis 425.

FIG. 15 shows a perspective view of a haptic device having apolypropylene elastic member, according to an embodiment of theinvention. As shown in FIG. 15, haptic device 500 includes actuator 510,elastic member 520 and mass 530. The elastic member 520 includesproximate portion 521, compliant portion 522 and distal portion 523. Theelastic member 520 is made of polypropylene, although other materials ofsimilar flexibility are possible. The distal portion 523 of elasticmember 520 is coupled to mass 530 by a slit in mass 530.

FIG. 16 shows a perspective view of a haptic device having apolypropylene elastic member, according to another embodiment of theinvention. In this embodiment, haptic device 600 includes actuator 610,elastic member 620 and mass 630. The elastic member 620 includesproximate portion 621, compliant portion 622 and distal portion 623. Theelastic member 620 is made of polypropylene, although other materials ofsimilar flexibility are possible. Distal portion 623 of elastic member620 is coupled to mass 630 by a bore within mass 630. Distal portion 623has a shape wider than compliant portion 622 thereby allowing distalportion 623 to fit snugly within the bore within mass 630.

FIG. 17 shows a perspective view of a mass and elastic member for ahaptic device, according to an embodiment of the invention. In thisembodiment, the shown portion of haptic device 650 includes elasticmember 680 and mass 670. The elastic member 680 includes proximateportion 681, compliant portion 682 and distal portion 683. The distalportion 683 is fit snuggly within a bore within mass 670 where the boreand distal portion 683 are larger than that shown in FIG. 16.

FIG. 18 shows a perspective view of a haptic device, according toanother embodiment of the invention. In this embodiment, haptic device700 includes actuator 710, elastic member 720 and mass 730. The elasticmember 720 includes proximate portion (not shown), compliant portion(not shown) and distal portion 722. In this embodiment, mass 730 extendsover the proximate portion and the compliant portion of the elasticmember 720.

Although the above-described embodiments show an elastic member couplingthe mass to the actuator, other configuration are possible for examplewhere the actuator is coupled to a base by the elastic member. In suchembodiments, the actuator is coupled to the mass without an interveningelastic member. As discussed below, FIGS. 21-26 show examples ofembodiments of a haptic device having an elastic member coupling anactuator to a base.

FIG. 19 shows a perspective view of a haptic device having an elasticmember coupling an actuator to a base, according to another embodimentof the invention. In this embodiment, haptic device 800 includes a base805, actuator 810, elastic element 820, mass 830, gear 840 and gear 850.In this embodiment, actuator 810 is elastically coupled to base 805 byelastic element 820. Actuator 810 is coupled to gear 840, which mateswith gear 850. In addition, actuator 810 includes arm 812, which iscoupled to sleeve 858 that surrounds shaft 855. Gear 850 rotates aboutshaft 855, which is grounded to base 805 by bushing 857. Mass 830 isrigidly coupled to gear 850 and rotates eccentrically about shaft 855.

When operating in the unidirectional mode, actuator 810 spins gears 840and 850, which in turn rotate mass 830 about shaft 855 in direction 860.Actuator 810 can be driven by, for example, a DC signal. Such a DCsignal can include, for example, modulation to provide controllabilityand bandwidth enhancement as described in U.S. application Ser. Nos.09/669,029 and 09/908,184; the disclosures of which are bothincorporated herein by reference.

When operating in the harmonic mode, actuator 810 moves with respect tobase 805 within a range of frequencies associated with the harmonicmode. More specifically, actuator 810 can be driven with an AC drivesignal (e.g., a signal having alternatively polarities). In response tothis AC drive signal, actuator 810 undergoes a rapid reversal of torque.This rapid reversal of torque combined with the rotational inertia ofmass 830 about shaft 855 causes actuator 810 to push against elasticmember 820 and housing 805, to which actuator 810 is elasticallycoupled. This motion of actuator 810 moves with respect to bushing 857.This results in harmonic motion of actuator 810 in direction 870.

FIGS. 20 and 21 show perspective views of a haptic device having anelastic member coupling an actuator to a base, according to anotherembodiment of the invention. As shown in FIGS. 20 and 21, haptic device900 includes a base 905, actuator 910, elastic element 920, mass 930,gear 940 and gear 950. In this embodiment, actuator 910 is elasticallycoupled to bass 905 by elastic element 920. Actuator 910 is coupled togear 940, which mates with gear 950. Gear 950 rotates about shaft 955,which is grounded to base 905. Mass 930 is rigidly coupled to shaft 957,which is rotationally coupled to gear 950. Consequently, mass 930rotates eccentrically about shaft 957.

FIGS. 22 and 23 show perspective views of a haptic device having anelastic member coupling an actuator to a base, according to yet anotherembodiment of the invention. Although similar to the embodiment shown inFIGS. 20 and 21, which has rotational axes perpendicular to the base,haptic device 1000 has its rotational axes parallel to the base. Thisarrangement allows haptic device 1000 to fit within a smaller verticalspace.

In some embodiments, the haptic device can include two actuators thatshare a common rotation axis and a common mass. Such embodiments allow,for example, the switch to and from the unidirectional mode and theharmonic mode based entirely on electrical signals. In other words, insuch embodiments, a mechanical escapement or other form of actuation isnot needed to switch to and from the unidirectional mode and theharmonic mode. Examples of such embodiments are discussed below inreference to FIGS. 24-26.

FIG. 24 shows a perspective view of a haptic device having two actuatorsthat share a common rotation axis and a common mass, according to anembodiment of the invention. As shown in FIG. 24, haptic device 1100includes base 1140, actuators 1110 and 1112, mass 1130 and elasticmember 1120. Actuators 1110 and 1112 share a common rotation axis 1115,along which mass 1130 is eccentrically coupled.

Base 1140 includes base portions 1142, 1144 and 1146, which collectivelyform a cradle-like structure that supports actuator 1110 along a pivotaxis 1118. Pivot axis 1118 is substantially perpendicular to rotationaxis 1115. Actuator 1110 can pivot about pivot axis 1118 within thecradle-like structure formed by base portions 1142, 1144 and 1146.Actuator 1112 is pivotally coupled to base portion 1148 of base 1140along pivot axis 1117, which is offset from rotation axis 1115. Actuator1112 is also suspended by elastic member 1120.

Similar to the devices described above, haptic device 1100 can operatein a unidirectional mode, a harmonic mode or a superposition mode. Whenoperating in the unidirectional mode, actuator 1110 and actuator 1112are driven, for example, by in-phase signals. This can allow the mass tobe rotated at a higher frequency than can be achieved by a singleactuator, and thereby a higher amplitude force can be achieved for agiven mass. This can cause mass 1130 to rotate strongly with double theforce otherwise typical of a haptic device with a single actuator.

When operating in the harmonic mode, actuator 1110 and actuator 1112 aredriven by signals that are, for example, 180° out of phase from eachother. In this harmonic mode, actuator 1110 reacts to the torqueproduced by actuator 1112 by imparting a vertical force to actuator 1112about the offset pivot axis 1117 at pivot joint location 1150.Consequently, actuator 1112 and mass 1130 move harmonically about anaxis defined by the pivot joint location 1150 and point 1119, which isthe intersection of axis 1115 and axis 1117.

Haptic device 1100 can be combined with a dual H-bridge amplifier (notshown) that drives actuators 1110 and 1112. In alternative embodimentswhere the doubling of force while in the unidirectional mode is notdesired, the motor windings of the actuators can be modified for moreefficient arrangement. Other adjustments can be made to achieve adesired haptic output. For example, the elastic member can be tuned, thelocation of the pivot joint can be adjusted, or the connection betweenthe two actuators can be adjusted. In addition, a blended drive schemecan be used that evens out the resonances of the system. The actuatorscan be controlled by, for example, a microprocessor controller to selectan operational mode. Alternatively, two PWM channels can be providedwith their own direction bits.

FIGS. 25 and 26 show perspective views of a haptic device having twoactuators that share a common rotation axis and a common mass, accordingto another embodiment of the invention. Haptic device 1200 includes base1240, actuators 1210 and 1212, mass 1230, elastic member 1220 and joint1260. Actuators 1210 and 1212 share a common rotation axis, along whichmass 1230 is eccentrically coupled. Base 1240 includes base portions1242 and 1244, which collectively form a cradle-like structure thatsupports actuator 1210 along a pivot axis 1218. Actuator 1212 is alsogrounded to housing 1240 by elastic member 1220, which is for example ahelical spring. Actuator 1212 is pivotally coupled to base 1240 alongpivot axis 1217, which is offset from rotation axis and includes joint1260 (e.g., a ball joint).

Haptic device 1200 operates similar to the haptic device described inreference to FIG. 17. In haptic device 1200, however, joint 1217 onpivot axis 1217 allows actuator 1212 movement in an additionaldirectional as well as motion about axis about 1218.

FIG. 27 shows a schematic top view of a haptic device having limitingstops, according to another embodiment of the invention. As shown inFIG. 27, haptic device 1300 includes actuator 1310, mass 1330, andelastic members 1320 and 1325. Mass 1330 is rigidly coupled to a shaft1315 of actuator 1310. Elastic members 1320 and 1325 each have one endgrounded. Elastic member 1320 is disposed within one side of a path ofmass 1330, and elastic member 1325 is disposed within another side ofthe path of mass 1330. Elastic members 1320 and 1325 act as limitingstops in the harmonic mode, which can be overcome in the unidirectionalmode.

In the harmonic mode, actuator 1310 is driven with an AC drive signal toproduce a bidirectional motion of mass 1330. When mass 1330 rotatessufficiently in one direction, for example direction 1350, mass 1330engages elastic member 1320 causing it to flex for example to position1320′. The flexed elastic member 1320 stores energy so that when thepolarity of the AC drive signal is reversed, mass 1330 is moved in theopposite direction 1340 and the flexed elastic member 1320 releases thestored energy. Similar to elastic member 1320, when mass 1330 rotatessufficiently in the other direction, for example direction 1340, mass1330 engages elastic member 1320 causing it to flex for example toposition 1325′, and the same process is repeated. The interaction ofmass 1330 with elastic members 1320 and 1325 contributes to the harmonicmotion of haptic device when operating in the harmonic mode.

In the unidirectional mode, actuator 1310 can be driven with a DC drivesignal having an amplitude sufficient to move mass 1330 beyond elasticmembers 1320 and 1330. Mass 1330 can then freely rotate in the samedirection continuously. To switch from the unidirectional mode to theharmonic mode, the amplitude of the DC drive signal can be reduced andthe AC drive signal provided. The amplitude of the DC drive signal canbe reduced to the point that the torque on mass 1330 is reduced so thatmass 1330 is deflected by elastic members 1320 and 1325. In alternativeembodiments, the haptic device can include a rotational sensor, whichcan sense the position of the rotating mass. This rotational sensor canindicate when the mass is deflected by the elastic members; at thispoint, the amplitude of the drive signal can be maintained and an ACdrive signal can be provided.

Although the elastic members 1320 and 1325 are shown as leaf springs,other types of elastic members are possible. For example, FIG. 28 showsa top view of a haptic device having limiting stops, according toanother embodiment of the invention. As shown in FIG. 28, haptic device1400 includes actuator 1410, mass 1430, and elastic members 1420 and1425. Mass 1430 is rigidly coupled to a shaft 1415 of actuator 1410.Elastic members 1420 and 1425 each have one end grounded and the otherend rotatably coupled to mass 1430 at pin 1440. In this embodiment,elastic members 1420 and 1425 are helical tension springs. Elasticmembers 1420 and 1425 act as limiting stops in the harmonic mode, whichcan be overcome in the unidirectional mode.

In the harmonic mode, actuator 1410 is driven with an AC drive signal toproduce a bidirectional motion of mass 1430. When mass 1430 rotatessufficiently in one direction, elastic member 1420 causes it to slowdown and move in an opposite direction. In the unidirectional mode,actuator 1410 can be driven with a DC drive signal having an amplitudesufficient to stretch elastic members 1420 and 1425 so that mass 1430moves in a complete circle and freely rotates in the same directioncontinuously.

In alternative embodiments, the elastic members can be magnets. Forexample, the actuator can include internal magnets to bias the rotor ofthe actuator to a desired “cogging” position. This arrangement providesa spring-return force on the rotor while in the harmonic mode. Foranother example, the actuator can include external magnets rather thaninternal magnets.

Although the limiting stops shown in FIGS. 27 and 28 are coupled toground, alternative embodiments are possible where the limiting stopsare not coupled to ground. For example, FIGS. 29 and 30 show aperspective view of a haptic device having stops integrally formed withan elastic member, according to an embodiment of invention. As shown inFIGS. 29 and 30, haptic device 1500 includes actuator 1510, an elasticmember 1520 and mass 1530. Elastic member 1520 includes a proximateportion 1521, a compliant portion 1522 and a distal portion 1525.Proximate portion 1521 of elastic member 1520 is coupled to the shaft1515 of actuator 1510. Distal portion 1525, which has a width greaterthan the compliant portion 1522, is coupled to mass 1530. Stops 1524 and1523 are integrally formed with elastic member 1520.

Stops 1524 and 1523 act as limiting stops while haptic device 1500 isoperating in the harmonic mode. In the harmonic mode, actuator 1510 isdriven with an AC drive signal to produce a bidirectional motion of mass1530. When mass 1530 rotates sufficiently in one direction, for exampletowards stop 1523, mass 1530 engages stop 1523 causing it to flex (see,for example, FIG. 30). Stop 1523 stores energy so that when the polarityof the AC drive signal is reversed, mass 1530 is moved in the oppositedirection and stop 1523 releases the stored energy. Stop 1524 similarlyengages mass 1530 on the opposite side of elastic member 1520.

Stops 1524 and 1523 each have a tapered shape that is thinner at thedistal end and wider at the end proximate to shaft 1515, from theperspective of a top view. In other words, from a top view, stops 1524and 1523 each have an angular dimension that is greater near shaft 1515than at the distal end. This tapered shape allows stops 1524 and 1523 toact progressively stiffer (i.e., to flex less) as mass 1530 engagesstops 1524 and 1523 with a greater force. As a result, as the hapticdevice 1500 nears resonance, stops 1524 and 1523 are engaged by mass1530 and the effective resonance shifts from what the resonance wouldotherwise be without the stops. Said another way, stops 1524 and 1523change the effective elasticity of elastic member 1520 thereby changingthe harmonic frequency of haptic device 1500.

In addition, stops 1524 and 1523 prevent over-travel of mass 1530 whileit is moving during operation. Moreover, stops 1524 and 1523 reducenoise associated with mass 1530 contacting any nearby surfaces thatcould otherwise occur without the presence of stops 1524 and 1523.

CONCLUSION

While various embodiments of the invention have been described above, itshould be understood that they have been presented by way of exampleonly, and not limitation. Thus, the breadth and scope of the inventionshould not be limited by any of the above-described embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

The previous description of the embodiments is provided to enable anyperson skilled in the art to make or use the invention. While theinvention has been particularly shown and described with referencepreferred embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the invention. Forexample, although various components such as the elastic members can bedescribed above as having unitary or integral construction, thesecomponents could be constructed from non-unitary construction.

1. A haptic device comprising: an actuator having a shaft; and a masscoupled to the shaft of the actuator, the actuator being elasticallycoupled to at least one of the mass and a base, the actuator and themass having a first operational mode associated with a range offrequencies and a second operational mode associated with a range offrequencies different from the range of frequencies associated with thefirst operational mode, the range of frequencies associated with thesecond operational mode including a harmonic frequency associated withthe elastic coupling of the actuator to at least one of the mass and abase, the actuator and the mass collectively having a third operationalmode that includes a superposition of the first operational mode and thesecond operational mode.
 2. A haptic device comprising: a rotaryactuator having a shaft; an elastic element coupled to the shaft of therotary actuator; and a mass coupled to the elastic element, the rotaryactuator, the elastic element and the mass collectively having a firstoperational mode associated with a range of frequencies and a secondoperational mode associated with a range of frequencies different fromthe range of frequencies associated with the first operational mode, thesecond operational mode being associated with a harmonic frequency ofthe elastic element, and the rotary actuator, the elastic element andthe mass collectively has a third operational mode associated with asuperposition of the range of frequencies of the first operational modeand the range of frequencies of the second operational mode.
 3. Thehaptic device of claim 2, wherein: the actuator is configured to receivea signal, the actuator is configured to rotate the shaft based on thesignal so that the rotary actuator, the elastic element and the masscollectively operate in one of the first operational mode, the secondoperational mode and the third operational mode.
 4. A haptic devicecomprising: a rotary actuator having a shaft; an elastic member coupledto the shaft of the rotary actuator; a mass coupled to the elasticelement; a first stop coupled to the rotary actuator at a location ofthe rotary actuator; and a second stop coupled to the rotary actuator ata location of the rotary actuator different from the location at whichthe first stop is coupled to the rotary actuator, the elastic memberbeing coupled to the rotary actuator between the location at which thefirst stop is coupled to the rotary actuator and the location at whichthe second stop is coupled to the rotary actuator, wherein the rotaryactuator, the elastic element and the mass collectively have a firstoperational mode associated with its own range of frequencies and asecond operational mode associated with its own range of frequenciesdifferent from the range of frequencies associated with the firstoperational mode, the second operational mode being associated with arange of effective harmonic frequencies defined, at least in pair, by ashape of the first stop and a shape of the second stop.
 5. A hapticdevice comprising: means for receiving a signal having at least one of afirst frequency component and a second frequency component; and meansfor rotating a mass, the means for rotating the mass configured torespond to the means for receiving in a first operational mode and asecond operational mode, the first operational mode being associatedwith the first frequency component, the second operational mode beingassociated with the second frequency component, the first operationalmode of the means for rotating being associated with a first range offrequencies, the second operational mode of the means for rotating beingassociated with a second range of frequencies, the first range offrequencies associated with the first operational mode of the means forrotating being different than the second range of frequencies associatedwith the second operational mode of the means for rotating, the meansfor rotating including an elastic member associated with a harmonicfrequency, the second range of frequencies associated with the secondoperational mode of the means for rotating including the harmonicfrequency, the harmonic frequency being greater than a frequency fromthe first range of frequencies associated with the first operationalmode of the means for rotating.
 6. The haptic device of claim 5,wherein: the means for rotating includes a first stop, a second stop andan elastic member, the range of frequencies associated with the secondoperational mode of the means for rotating including a frequency greaterthan a frequency from the range of frequencies associated with the firstoperational mode of the means for rotating, and the range of frequenciesassociated with the second operational mode of the means for rotatingincluding the harmonic frequency is a range of effective harmonicfrequencies defined, at least in part, by a shape of the first stop anda shape of the second stop.